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MANUAL OF ENTOMOLOGY

Chermes, which have a complicated cycle of sex form«, migrantn
and food-plants.
The greatest vine pest was Phylloxera rafttatrix, an American
species introduced to Europe; the greatest apple pent in
Eriosoma laniyem, introduced to England about 1780, and
probably itnelf indigenous to America. Others are major
pests on wheat, cotton, hops, mustard, plum, melon, etc. Their
control depends upon a study of food plants, natural enemies
and climatic influences ; and while spraying is largely done, on
hops for inntance, it is a wasteful and unsatisfactory method.
ALKURODID/K
White fly, Mealy wings.
Two pairs of wings, sloped over the abdomen ; the win^s
and body covered with mealy wax ; the nymph flat, scale-like
after the first moult, usually with a waxy fringe. The
rectum opens on a dorsal process, which lies under a plate,
in the vasiform orifice.
Mealy wings are, in the adult stage, small, white, or black
and white, moth-like insects, found on plants. Colour probably
has no significance. The white waxy covering is formed of
short curled waxy filaments, secreted from unicellular glands
and spread over the body, legs and wings, probably as a pro-
tection.
The adult has a distinct head, with seven-jointed aintenna?,
compound eyes, and two ocelli; the mouth-parts are much an
in Aphids, with long styletn and a short labium, the stylets
not actuated from the head, but by the labium. Spiracles arc*
situated on the mesothorax and on abdominal one* and neven.
At the dorsal apex of the abdomen in a semicircular orifieo,
partly covered by a plate, under which lies a process carrying the
anal opening. There are glandular areas on the ventral surface*
of abdominal segments two and three, secreting the waxy
filaments. The pseudovitellus is visible inside the abdomen
about the second, and third segments.
The male has clampers, thc^ female a short ovipositor. An a
rule both sexes are present., but Almrodw wporariorum in
frequently parthenogenetic.